1. Field of the Invention
This invention relates to an antiskid control system for a vehicle.
2. Description of the Prior Art
There are various known antiskid control systems which have been contrived to prevent occurrence of a locked state of wheels of a vehicle during brake application by reducing any excessive wheel braking force for adequate contact of wheels with the road surface. An example of antiskid control systems of this kind is disclosed, for example, in U.S. Pat. No. 4,215,902.
The antiskid control system of this kind must meet the following requirements: When any variation of the braking hydraulic pressure within the braking device is transmitted as it is to the master cylinder device during antiskid control, the brake pedal of the vehicle is affected by a kick back resulting from the variation. This gives an abnormal feeling to the operator of the vehicle and, therefore, must be prevented. In addition to this, at the start of antiskid control, if braking pressure fluid is introduced into the braking device in an excessively large amount, a wheel locking state would saliently appear. To avoid the locked state, therefore, excessive introduction of the braking pressure fluid into the braking device should be avoided as much as possible. Further, the increase, decrease or retention of braking hydraulic pressure must be controlled promptly and stably as necessary according to the wheel velocity. Therefore, the antiskid control system must be designed with these requirements duly taken into consideration.